In Cubase 7.5.10 x64 (Windows 7 SP1 x64), I can link the branches to a midi controller, but nothing happens when I turn a knob...

I remember it working in the old (32 bit) version.

This should work exactly as in 1.0. The individual branches are not directly controllable by MIDI but exposed as VST parameters that can (depending on host) be mapped to your MIDI controller. If the host can move the VST parameter, then it should work.